Painted Scene with Lighting
If you look closer to this tutorials, you'll notice, that they don't really paint lighting conditions but more like Ambient occlusion and some highlights, that are similar for each side of the object. In the tutorial you linked to, you can see the same amount of shadow under the top part on each side, The same with the highlights on cracks and tiles. The same on each side.Try to copy this effect while creating your painted textures. This will suggest some details, but won't interfere too much with added lighting.